There is simply no incident response action that doesn't include a communications component any more - whether you conduct threat hunting operations, traditional casework, or post-mortem incident response, understanding the nature of how systems have communicated is critical to success. Even in disk- and memory-based incident response work, artifacts that clarify a subject's network actions can be keystone findings you can't afford to miss. Whether you are handling a data breaches, intrusion scenario, employee misuse, or threat hunting (proactively trawling your organization's data stores for evidence of an undiscovered compromise), the need to effectively examine and interpret network artifacts is here to stay.

FOR572: ADVANCED NETWORK FORENSICS AND ANALYSIS was built from the ground up to cover the most critical skills needed to mount efficient and effective post-incident response investigations. We focus on the knowledge and analytic approach needed to incorporate a network perspective into proactive hunting or traditional casework. Even the most skilled attacker can't fully escape leaving some evidence of communications on the network - so you'll learn the skills to identify reconnaissance, exploitation, operational, command-and-control, and data exfiltration phases of an incident. If you're chasing leads on an existing case or seeking evidence of a compromise you haven't yet discovered, the network is the key to success. Put another way: Bad guys are talking - we'll teach you to listen.

This course covers the tools, technology, and processes required to integrate network evidence sources into your investigations, with a focus on efficiency and effectiveness. You will leave this week with a well-stocked toolbox and the knowledge to use it on your first day back on the job. We will cover the full spectrum of network evidence, including high-level NetFlow analysis, low-level pcap exploration, ancillary network log examination, and more. We cover how to leverage existing infrastructure devices that may contain months or years of valuable evidence as well as how to place new collection platforms while an incident is already under way.

Whether you are a consultant responding to a client's site, a law enforcement professional assisting victims of cybercrime and seeking prosecution of those responsible, or an on-staff forensic practitioner, this course offers hands-on experience with real-world scenarios that will help take your work to the next level. Previous SANS SEC curriculum students and other network defenders will benefit from the FOR572 perspective on security operations as they take on more incident response and investigative responsibilities. SANS Forensic alumni from 408 and 508 can take their existing knowledge and apply it directly to the network-based attacks that occur daily. In FOR572, we solve the same caliber of real-world problems without any convenient hard drive or memory images.

The hands-on exercises in this class cover a wide range of tools, including the venerable tcpdump and Wireshark for packet capture and analysis; NetworkMiner for artifact extraction; and open-source tools including nfdump, tcpxtract, Logstash, and more. Through all of these exercises, your shell scripting abilities will come in handy to make easy work of ripping through hundreds and thousands of data records.

FOR572 is truly an advanced course - we hit the ground running on day one. Bring your entire bag of skills: forensic techniques and methodologies, networking (from the wire all the way up to user-facing services), Linux shell utilities, and everything in between. They will all benefit you throughout the course material as you FIGHT CRIME. UNRAVEL INCIDENTS...ONE BYTE (OR PACKET) AT A TIME.

For multi-course live training events, there will be a set up time from 8:00-9:00am on the first day only to make sure that computers are configured correctly to make the most of class time. All students are strongly encouraged to attend.

Course Syllabus

FOR572.1: Off the Disk and Onto the Wire

Overview

Focus: Although many concepts of network forensics are similar to those of any other digital forensic investigation, the network presents many nuances that require special attention. Today you will learn how to apply what you already know about digital forensics and incident response to network-based evidence. You will also become acclimated to the basic tools of the trade.

Network data can be preserved, but only if captured directly from the wire. Whether tactical or strategic, packet capture methods are quite basic. You will re-acquaint yourself with tcpdump and Wireshark, the most common tools used to capture and analyze network packets, respectively. However, since long-term full-packet capture is still uncommon in most environments, many artifacts that can tell us about what happened on the wire in the past come from devices that manage network functions. You will learn about what kinds of devices can provide valuable evidence and at what level of granularity. We will walk through collecting evidence from one of the most common sources of network evidence - a web proxy server - then go hands-on to find and extract stolen data from the proxy yourself.

The Linux SIFT virtual machine, which has been specifically loaded with a set of network forensic tools, will be your primary toolkit for the week.

FOR572.2: NetFlow Analysis, Commercial Tools, and Visualization

Overview

FOCUS: Network connection logging, commonly called NetFlow, may be the single most valuable source of evidence in network investigations. Many organizations have extensive archives of flow data due to its minimal storage requirements. Since NetFlow does not capture any content of the transmission, many legal issues with long-term retention are mitigated. Even without content, NetFlow provides an excellent means of guiding an investigation and characterizing an adversary's activities from pre-attack through operations.

Just as photos from high-altitude reconnaissance aircraft and satellites are instrumental in national policy decisions, NetFlow data can provide a network investigator with extremely high-value intelligence about network communications. The key to extracting that value is in knowing how to use NetFlow evidence to drive more detailed (and labor-intensive) investigative activities.

In this section, you will learn what data items NetFlow can provide, and the various means of collecting those items. As with many such monitoring technologies, both commercial and open-source solutions exist to query and examine NetFlow data. We will review both categories and discuss the benefits and drawbacks of each.

In the same vein, presenting concise findings from extremely large data sources is an important skill. A network forensicator should be able to aggregate and visually present findings, especially when faced with a years-long compromise incident. Expressing findings supported with visualizations can provide a much clearer picture than words alone.

Exercises

NetFlow Analysis

Identifying Lateral Movement

Commercial Network Forensic Tools

Visualizing NetFlow Data

CPE/CMU Credits: 6

Topics

NetFlow Analysis and Collection

Origins and evolution

NetFlow protocol

Architectural components

Open-Source Flow Tools

Using open-source tool sets to examine NetFlow data

nfcapd and nfdump

nfsen

SiLK

Commercial Network Forensics

Common commercial platforms that you may encounter

Using existing platforms and tools in a client environment

Trade-offs between commercial and open-source solutions

Visualization Techniques and Tools

Making big data sources easily digestible

Visually identifying trends and outliers

Dynamic Host Configuration Protocol (DHCP) and Domain Name Service (DNS)

DHCP

Lease/re-lease process

Server configuration

Server logging

DNS

Architecture and core functionality

Tunneling

Fast flux

FOR572.3: Network Protocols and Wireless Investigations

Overview

Focus: Network protocols are the foundation on which all network communications build. Without an understanding of how the most fundamental protocols behave, further examination and investigation is simply impossible. More importantly, without honing the skills necessary to learn new protocols, the network forensicator will be unprepared for the future in the rapidly evolving field in which we work.

This section covers some of the most common and fundamental network protocols that you will likely face during an investigation. We will cover a broad range of protocols including the Dynamic Host Configuration Protocol, which "glues" together layers two and three on the OSI model, and Microsoft's Remote Procedure Call protocol, which provides all manners of file, print, name resolution, authentication, and other services.

While no one course could ever exhaustively cover the dizzying list of protocols used in a typical network environment, you will build the skills needed to learn whatever new protocols may come your way. The "learn how to learn" skill is critical, as new protocols are being developed every day. Advanced adversaries develop their own protocols, too, and as you will see later in this class, successfully understanding and counteracting an adversary's undocumented protocol is a similar process to learning those you will see in this section.

Finally, we will address the forensic aspects of wireless networking. We will cover similarities with and differences from traditional wired network examination, as well as what interesting artifacts can be recovered from wireless protocol fields. Some inherent weaknesses of wireless deployments will also be covered, including how attackers can leverage those weaknesses during an attack, and how they can be detected.

Exercises

HTTP Profiling

Wireless Packet Analysis: Analysis of a Wireless Capture

Documenting SMB Session from pcap

CPE/CMU Credits: 6

Topics

Hypertext Transfer Protocol (HTTP)

Forensic value

Request/response dissection

Useful HTTP fields

Monkey wrenches

Artifact extraction

Network Time Protocol (NTP)

Protocol fundamentals

Use in investigations (*NIX and Windows)

Protocol dissection

File Transfer Protocol (FTP)

History and current use

Shortcomings in today's networks

Capture and analysis

Wireless Network Forensics

Translating analysis of wired networks to the wireless domain

Capture methodologies

Useful protocol fields

Inherent weaknesses

Simple Mail Transfer Protocol (SMTP)

Lifecycle of an email

Adaptations and extensions

Microsoft Protocols

Architecture and capture positioning

Exchange/Outlook

SMB v1, v2, and v3

Sharepoint and internal web sites

FOR572.4: Logging, OPSEC, and Footprint

Overview

Focus: Full-packet capture evidence is often unavailable. Even when it is, the period of coverage rarely extends past a few weeks. Incidents frequently go undiscovered for months or years, so we must turn to what evidence does exist to characterize the network activity around the time of original compromise. Existing infrastructure assets can also be reconfigured to gather more or higher fidelity evidence during an incident response.

Log data is one of the unsung heroes in the realm of network forensics. While the near-perfect knowledge that comes with full-packet capture seems ideal, it suffers from several shortfalls. It is often unavailable, as many organizations have not yet deployed or cannot deploy comprehensive collection systems. When they are in use, network capture systems quickly amass a huge volume of data, which is often difficult to process effectively and must be maintained in a rolling buffer covering just a few days or weeks.

Understanding log data and how it can guide the investigative process is an important network forensicator skill. Examining network-centric logs can also fill gaps left by an incomplete or nonexistent network capture.

In this section, you will learn various logging mechanisms available to both endpoint and network transport devices. You will also learn how to consolidate log data from multiple sources, providing a broad corpus of evidence in one location. As the volume of log data increases, so does the need to consider automated analytic tools. You will learn various solutions that accomplish this, from tactical to enterprise-scale.

Another benefit available in the network domain of incident response is the ability to repurpose infrastructure devices so they will better serve an ongoing investigation. When properly executed, this practice becomes an invaluable component in the incident response cycle. As incident responders acquire intelligence, they tune collections to better track the adversary's actions, which then begets better intelligence. This process requires special care, however, since interaction with active devices can create additional network traffic, and therefore, additional source evidence. As in many forensic processes, the key is to take measured steps, make minimal changes, and keep detailed documentation of each step.

Finally, the network domain provides some significantly different challenges than the traditional computer forensic domain. The process of analysis and research is an active one - simply looking up a domain name from a log file can alert an attacker to the response team's status in the investigation. You will learn which types of activities should be avoided and which can be mitigated to better ensure operational security.

FOR572.5: Encryption, Protocol Reversing, and Automation

Overview

Focus: Advancements in common technology have made it easier to be a bad guy and harder for us to track them. Sound encryption methods are readily available and custom protocols are easy to develop and employ. Despite this, there are still weaknesses even in the most advanced adversaries' methods.

Encryption is frequently cited as the most significant hurdle to effective network forensics - and for good reason. When properly implemented, encryption can be a brick wall in between an investigator and critical answers. However, technical and implementation weaknesses can be used to our advantage. Even in the absence of these weaknesses, the right analytic approach to encrypted network traffic can still yield valuable information about the content. We will discuss the basics of encryption and how to approach it during an investigation. The section will also cover flow analysis to characterize encrypted conversations.

In addition, this section addresses how network forensicators can rebuild fragmented payloads in order to reconstruct original communication streams. We will then address undocumented protocols and how to derive intelligence value with limited or nonexistent knowledge of the protocol.

Finally, we will discuss how to pivot labor-intensive tasks into scalable solutions through automation. Whether chaining single-use tools together to create an end-to-end solution or developing a new tool using various existing forensically minded libraries, your methods can be applied as easily to terabytes of live-source data as they can to a 2-gigabyte pcap.

FOR572.6: Network Forensics Capstone Challenge

Overview

Focus: This section will combine all of what you have learned prior to and during this week. In groups, you will examine network evidence from a real-world compromise by an advanced attacker. Each group will independently analyze data, form and develop hypotheses, and present findings. No evidence from endpoint systems is available - only the network and its infrastructure.

Students will present their findings at each stage of the exercise. This will test their understanding of the evidence and ability to articulate and support their hypotheses. The audience will include senior-level decision makers, so all presentations must include executive summaries as well as technical details. Time permitting, students should also include recommended steps that could help to prevent, detect, or mitigate a repeat compromise.

Exercises

Capstone Exercise

CPE/CMU Credits: 6

Topics

Network Forensic Case

Analysis using only network-based evidence

Determine the original source of an advanced attacker's compromise

Identify the attacker's actions while in the victim's environment

Confirm what data the attacker stole from the victim

Reporting

Present executive-level summaries of your findings at each stage of the exercise

Document and provide low-level technical backup for findings

Establish and present a timeline of the attacker's activities

Time permitting, provide recommendations on how the victim can prevent, detect, or mitigate a repeat compromise by the same or another similarly advanced attacker

Additional Information

Laptop Required

!!IMPORTANT - BRING YOUR OWN SYSTEM CONFIGURED USING THESE DIRECTIONS!!

You can use any 64-bit version of Windows, Mac OSX, or Linux as your core operating system that also can install and run VMware virtualization products.

It is critical that your CPU and operating system support 64-bit so that our 64-bit guest virtual machine will run on your laptop. VMware provides a free tool for Windows and Linux that will detect whether or not your host supports 64-bit guest virtual machines. For further troubleshooting, this article also provides good instructions for Windows users to determine more about the CPU and OS capabilities. For Apple OS X users, please use this support page from Apple to determine 64-bit capability.

Please download and install VMware Workstation 11, VMware Fusion 7, or VMware Player Plus 7 or higher versions on your system prior to class beginning. If you do not own a licensed copy of VMware Workstation or Fusion, you can download a free 30-day trial copy from VMware. VMware will send you a time-limited serial number if you register for the trial at their Web site. VMware Player Plus is a free download that does not need a commercial license. Please note that other virtualization software is not supported in the lab environment, and may not successfully run the supplied virtual machines.

MANDATORY FOR572 SYSTEM HARDWARE REQUIREMENTS:

CPU: 64-bit Intel x64 2.0+ GHz processor or higher based system is mandatory for this class (Important - Please Read: a 64-bit system processor is mandatory! Test your VMware Software before coming to class. Some BIOS configurations may require special settings (such as "VT-x" and/or "no-execute memory protection") to allow virtualization. You must also have administrative access to your BIOS, in case changes are needed when in class.)

RAM: 8 GB (Gigabytes) of RAM minimum

Host Operating System: Fully patched and updated Windows (7+) or Apple OS X (10.10+) that can install and run VMware virtualization products (VMware Workstation, VMware Fusion, or VMware Player). Please note: It is necessary to fully update your host operating system prior to the class to ensure you have the right drivers and patches installed to utilize the latest USB 3.0 devices. Students that use Linux hosts are warned the wide variety of Linux distributions prohibits testing our exercises on this platform - your mileage may vary. Those that use a Linux host must be able to access ExFAT partitions using the appropriate kernel or FUSE modules.

Networking: Wireless 802.11 B, G, or N

Hardware:

USB 2.0 or higher Port(s) (Note: Some endpoint protection software prevents the use of USB devices - test your system with a USB drive before class to ensure you can load the course data.)

200 Gigabyte Host System Hard Drive minimum

~80 Gigabytes of Free Space on your System Hard Drive (Note: The free space is needed for the SIFT Workstation VM and the evidence we will be adding to your system)

MANDATORY FOR572 SYSTEM SOFTWARE REQUIREMENTS (Install the following prior to the beginning of the class):

The student should have Local Administrator Access within their host operating system as well as the BIOS for the laptop, if applicable. We have found several cases where the BIOS virtualization settings must be changed from their factory defaults prior to running 64-bit operating systems as VMware guests.

Bring/install any other forensic tool you feel could be useful (Maltego, NetWitness, etc). For the final challenge at the end of the course, you can utilize any forensic tool, including commercial capabilities, to help you and your team. If you have any dongles, licensed software, etc. you are free to use them.

Although SANS is not responsible for the security of your personal effects, you might want to consider bringing a laptop lock.

If you have additional questions about the laptop specifications, please contact laptop_prep@sans.org.

Who Should Attend

Incident response team members and forensicators who are expanding their investigative scope from endpoint systems to the network

Network engineers who are proactively orienting their networks to best meet investigative requirements

Information technology professionals who want to learn how network investigations take place

Anyone interested in computer network intrusions and investigations who has a solid background in computer forensics, information systems, and information security

What You Will Receive

Custom distribution of the Linux SANS SIFT Workstation Virtual Machine with over 500 digital forensics and incident response tools prebuilt into the environment, including network forensic tools added just for this course

"Although FOR572 is a network forensics class, it gets exactly right what most incident response courses get wrong. Instead of focusing on specific exploits and malware that quickly become outdated, 'Advanced Network Forensics' taught me about the full range of evidence sources available and how to effectively mine them for clues. Even more importantly, FOR572 taught me how to use different evidence sources to fill in missing gaps. This is critical, as most environments or incidents will not have every type of evidence available. A large scale APT breach will not have full packet capture available for what could be over a year of attacker activity, but making effective use of network log files can fill in those gaps. It also dove into advanced topics like analyzing unknown protocols, which is an important skill when dealing with the ever-evolving landscape of malware and odd but legitimate applications. Finally, the network forensics capstone investigation is a small but realistic simulation of an APT breach. Having to perform a realistic investigation under the pressure of limited in-class hours felt much like the pressures of investigating a live incident under the pressure of stopping ongoing data theft. It is an excellent class, and I would definitely recommend it to anyone wanting to bring their IR skills to the next level." - Alexander Bond, Mandiant

"The SANS Institute is currently the leader in the commercial IR and computer forensic training market. They have a large number of quality courses." - Luttgens, Jason; Pepe, Matthew; Mandia, Kevin. Incident Response & Computer Forensics, Third Edition - July 2014

"SANS Institute has many valuable assets - Phil Hagen is one of them." - Anonymous

"Loving the detailed and mutli-layered labs. I have been doing the walkthroughs for time sake but will revisit in depth later." - Anonymous

Author Statement

When I first became interested in computer and network security in the mid-1990s, the idea of "attacking" another computer network was a concept still firmly in science fiction. Today, commercial, governmental, military, and intelligence entities have robust, integrated information security processes. Within the forensic community, we have seen developments that show the agility we must have to remain effective in the face of dynamic adversaries. Disk-based forensic practices will remain the keystone of digital forensics for the foreseeable future - events ultimately occur on endpoints, after all. Memory forensics has formalized how we address the components of a compromised system that avoid the disk.

We created FOR572: Advanced Network Forensics and Analysis to address the next domain of digital forensics. Many enterprises have grown to the scale that identifying which endpoints to examine is a significant challenge and the network has become its own medium for incident response and investigation. Our ability to use evidence from all kinds of network devices as well as from captured network data itself will be critical to our success in addressing threats today and tomorrow. From low-grade "script kiddie" attacks to long-term, strategic state-sponsored espionage activity, the network is one of the few common elements found throughout the life cycle of an incident. FOR572 will provide you with the tools and methods to conduct network investigations within environments of all sizes, using scenarios developed from real-world cases. You will finish the course with valuable knowledge that you will use the first day back on the job, and with the methodologies that will help address the next generations of adversaries' capabilities.

- Phil Hagen

When I first started my career in computer security, the term "advanced persistent threat" was unknown, yet I had personally recovered terabytes of data obtained from both commercial and government networks. The biggest cybersecurity threat in the news was the latest worm that would propagate through unsuspecting systems and cause more of a nuisance than actual destruction. What was known as the Russian Business Network wasn't even around yet. Network security monitoring was still in its infancy, with very little formal documentation or best practices, most of which were geared towards system administrators. While the Internet has continued to expand, we have all become more interconnected and the threat against our networks continues to grow. We wrote FOR572 as the class we wish we had when we were entering the field of network forensics and investigations - a class that not only provides background when needed, but is primarily tailored toward finding evil using multiple data sources and performing a full scope investigation. I am confident this course provides the most up-to-date training covering topics both old and new, based on real-life experiences and investigations.